Laser-assisted thermal separation of tissue

ABSTRACT

A laser-assisted method for fully or partially separating tissue such as collagen-containing tissue is provided. In one embodiment, the method pertains to a capsolurorhexis whereby the laser-assisted method is applied to the lens capsule. A light-absorbing agent is added into or onto the tissue. A light beam with a wavelength capable of being absorbed by the light absorbing agent is then directed at the tissue to cause a thermal effect at the tissue following a predetermined closed curve with the goal to avoid irregularity or potential tears in the resulting rim of the tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.60/995,792, filed on Sep. 28, 2007, which is incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to surgeries and procedures for removingor separating tissue. In particular, the invention relates methods anddevices for performing a capsulorhexis.

BACKGROUND OF THE INVENTION

Cataracts are a common cause for poor vision. They are the leading causeof blindness with a prevalence of over 20M worldwide. In addition, thereare at least 100M eyes with cataracts causing visual acuity of less that6/60 in meters (or 20/200 in feet). Cataract extraction is the mostcommonly performed surgical procedures in the world with estimates of 10million cases worldwide and 2 million cases being performed annually inNorth America. There are three types of cataract extraction:intracapsular, small incision cataract and phacoemulsification.

Currently, intracapsular surgery is commonly performed in the developingcountries where there are less resources. In this procedure both theopacified natural lens and the lens capsule are removed together.

In small incision cataract surgery and phacoemulsification the opacifiednatural lens is removed while leaving the elastic lens capsule intact toallow implantation and retention of the intraocular lens (IOL). One ofthe more critical surgical component is the capsulorhexis.

Capsulorhexis is the incision in the lens capsule to permit removal ofthe lens nucleus and cortex. The lens capsule is a transparent,homogeneous basement membrane that is made up of collagen-like protein.It has elastic properties without being composed of elastic fibers. Thecapsule has a smooth surface contour except at its equator where thezonules attach.

Ideally the capsulorhexis creates a symmetric circular incision,centered about the optical axis and is sized appropriately for the IOLand patient's condition. The mechanical integrity around the newlyformed incision edge needs to be sufficient to withstand the forcesexperienced during cataract extraction and IOL implantation. Bymaintaining integrity of the remaining capsule, the IOL haptics arelocated in proximity of the capsule equator to allow location of theIOL. Postoperatively the newly formed capsule rim hardens and theopening contracts providing further strengthen and structural supportfor the IOL to prevent dislocation and misalignment. Because of thispostoperative contraction it is important that the opening diameter andthe IOL optic diameter are purposefully mismatched, otherwise theresultant pressures may cause the IOL to be dislocate.

The current standard of care for capsulorhexis is Continuous CurvilinearCapsulorhexis (CCC). The concept of the CCC is to provide a smoothcontinuous circular opening through the anterior lens capsule forphacoemulsification and insertion of the intraocular lens minimizing therisk of complications including errant tears and extensions. Currently,the capsulorhexis is performed manually utilizing forceps or a needle.The technique is dependent on applying a shear force and minimizingin-plane stretching forces to manually tear the incision.

The size of the capsulorhexis is determined by technique, the zonulesstrength and IOL optic diameter. Zonular strength is assessed prior tocapsulorhexis. If the zonules appear strong then the capsulorhexisdiameter should measure about 4-5 mm being about 0.5 to 1.0 mm smallerthan the IOL optic diameter and centered on the optical axis. Thisprovides overlap with the IOL and some margin for error. If theassessment shows a generally loose lens diaphragm then the capsulorhexisshould made about 5 to 7 mm in diameter being about 0.5 to 1.0 mm largerthan the IOL optic diameter, again centered on the optical axis. If thezonular strength assessment shows asymmetric weakness the capsulorhexisshould still be 5 to 7 mm in diameter being 0.5 to 1.0 mm larger thanthe IOL optic diameter, but located off-center away from the possibledehiscence. The would allow the IOL optic to be aligned and centered upwith the capsulorhexis when the haptics is orientated toward thequadrant of zonular weakness. Larger diameter capsulorhexis are moredifficult because the steepness of the capsule wall increases towardsthe capsule equator, thus its harder to limit the shear forces withoutstretching the capsule, and the probability increases of a rhexisescape, i.e., an errant tear.

Errant tears are radial rips and extensions of the capsulorhexis towardsthe equator, moreover if a zonular attachment is encountered the tear issent directly out to the capsular fornix and possibly through to theposterior of the capsule. Furthermore, posterior capsule te arsfacilitate the nucleus being “dropped” into the posterior chamberresulting in further complications.

Further problems that may develop in capsulorhexis are related toinability of the surgeon to adequately visualize the capsule due to lackof red reflex, to grasp it with sufficient security, to tear a smoothsymmetric circular opening of the appropriate size or technicaldifficulties related to maintenance of the anterior chamber depth afterinitial opening, small size of the pupil, or the absence of a red reflexdue to the lens opacity. Additional complications arise in olderpatients with weak zonules and very young children that have very softand elastic capsules, which are very difficult to mechanically rupture.

Errant tears and other problems can be managed to some degree with theaddition of dense viscoelastics and relaxing incisions to assist instabilization of the capsule rim. If need be a two-stage capsulorhexistechnique can be required to rescue a situation or for the formation ofa second large capsulorhexis. Specifically, after creating an initialcapsulorhexis, the anterior cortex is removed with aspiration andirrigation and capsule is refilled with viscoelastic to stabilize thecapsule and the capsulorhexis is enlarged by tearing larger secondcapsulorhexis.

Further stress is applied to the capsulorhexis in phacoemulsificationand implantation of the IOL, if the capsulorhexis is discontinuous or ifthe force is too great the capsulorhexis may cause a radial tear. Thisis dealt with as above. Furthermore if the posterior capsule integrityis damaged during the cataract surgery (i.e., a posterior capsule rent)dense viscoelastic is added to preserve its shape and a posteriorcapsulorhexis is performed, to salvage the integrity and strength of thecapsule around its equator such that an IOL can be implanted.

Most current cataract surgeries are performed with the aid ofphacoemulsification and typically includes the following eightheensteps.

-   -   1. Pupil Dilation    -   2. Local Anesthesia    -   3. Placement of the lid speculum    -   4. Entry into the eye through a small incision (typically 2-3 mm        in length, at the edge of the cornea)    -   5. Viscoelastic injected into the anterior chamber and to        maintain the volume and shape of the Anterior chamber and cornea        during the rest of the procedure    -   6. Zonule function test    -   7. Capsulorhexis    -   8. Hydrodissection are intended to identify and soften the        nucleus for the purposes of removal from the eye.    -   9. Hydro-delineation increases the distance between the nucleus        and the posterior capsule, thus providing a safety zone.    -   10. Nuclear cracking or chopping if needed    -   11. Ultrasonic with aspiration and irrigation are used to sculpt        and emulsification of the nucleus used to sculpt the relatively        hard nucleus of the lens.    -   12. Aspiration of the residual soft cortex    -   13. Capsular polishing    -   14. once the capsule is empty further addition of viscoelastic        to maintain the volume and shape of the capsule    -   15. Implantation of the artificial IOL    -   16. Centration of the IOL    -   17. Viscoelastic removal    -   18. Wound sealing/hydration (if needed)

Following cataract surgery there is a rapid 1-2 days response where thecapsule hardens and the capsule contraction starts. This continues overa 4-6 week period where fibrosis of the capsulorhexis and IOL opticinterface, and the haptic and capsule interfaces also occur. Even beyondone year the capsule continues to contract to a lesser degree, thuspositioning the capsulorhexis is a critical factor in the long-termsuccess.

Following cataract surgery one of the principal sources of visualmorbidity is the slow development of opacities in the posterior lenscapsule, which is generally left intact during cataract surgery as amethod of support for the lens, and also as a means of preventingsubluxation posteriorly into the vitreous cavity. It has been estimatedthat the complication of posterior lens capsule opacification occurswithin 5 years of surgery with a 10% incidence. This problem is thoughtto occur as a result of epithelial and fibrous metaplasia along theposterior lens capsule centrally from small islands of residualepithelial cells left in place near the capsule equator. The Q-switchNd:YAG lasers are utilized as to perform a noninvasive posteriorcapsulotomy to remove the opacification from the proximity of theoptical axis.

Accordingly, there is a need in the art to provide new ophthalmicmethods, techniques and apparatus to advance the standard of care forcapsulorhexis.

SUMMARY OF THE INVENTION

The present invention provides a laser-assisted method for separatingtissue such as collagen-containing tissue. In one embodiment, the methodis a capsolurorhexis whereby the laser-assisted method is applied to thelens capsule.

A light-absorbing agent is added into or onto the tissue. A light beamwith a wavelength capable of being absorbed by the light absorbing agentis then directed at the tissue to cause a thermal effect at the tissue.The light beam is: (i) characterized to remain at a sub-ablation levelof the tissue or (ii) characterized to cause melting of the tissue. Thelight beam could either cause a full or partial separation, cutting orpuncture of the tissue.

A predetermined closed curve is defined at the tissue. This curvedefines an interior and an exterior. The light beam is directed at aninitial and interior point of the predetermined closed curve. Once aninitial puncture or partial/full separation has been achieved, the lightbeam continues and is further directed starting from the initial andinterior point of the predetermined closed curve along the remainingpath of the predetermined closed curve until at least the curve isclosed. In one embodiment, the continued light beam ends at a final andinterior point of the predetermined closed curve.

The initial and the continuing light beam(s) could be the same type oflight beam or different types of light beams. In a preferred embodiment,the light beam is a laser beam from a CW laser. A CW laser is preferredfor at least the continuing light beam to allow for a single pass alongthe curve to avoid irregularity or potential tears in the resulting rimof the tissue. The exterior path of the predetermined closed curve ispreferably substantially circular or ellipsoidal in the application of acapsulorhexis but is not limited to these shapes in other applications.

Visualization patterns could be added and projected at the tissue whichwill aid in the procedure. The visualization patterns useful in thisinvention (i) are different from the predetermined closed curve or (ii)include of at least 3 set of dots, wherein each of the set of dots isdistributed along the interior-exterior border of the predererminedclosed curve.

BRIEF DESCRIPTION OF THE FIGURES

The present invention together with its objectives and advantages willbe understood by reading the following description in conjunction withthe drawings, in which:

FIG. 1 shows according to an embodiment of the present invention atranverse plane view of some parts of the eye (lens capsule 110, IOL120, dialated iris 140, cornea 160 and anterior chamber 170), a lightabsorbing agent 130 and a light beam 150.

FIG. 2 shows according to an embodiment of the present invention a sideview of the lens capsule 110 whereby the tissue (in this example lenscapsule 110) has been separated at 210 into two parts, e.g. an exteriorpart 110-E and an interior part 110-I. FIG. 2 also shows the contractedand shrinked ends 220-E and 220-I.

FIG. 3 shows according to an embodiment of the present invention acoronal plane view from an anterior direction of a tissue (in thisexample lens capsule 110) with a predetermined closed curve 310. It isimportant to note that the predetermined closed curve starts with aninitial point inside of the closed curve. In one embodiment, thepredetermined closed curve ends at any point where the curve becomesclosed. In another embodument, the predetermined curve end withend-point within the interior area.

FIGS. 4A-B show according to an embodiment of the present invention avisualization pattern 410, which preferably coincides with the perimeterof the closed curve (e.g. a circular pattern in this particularexample). It is important to note that the visualization pattern 410does not include the initial and end paths inside the interior area.FIGS. 4A-B also show another visualization pattern with at least 3 setof dots 420 to assist in focusing the light beam(s), whereby the set ofdots preferebly are visualized along the interior-exterior border of theclosed curve 310. FIG. 4A shows 4 sets of dots and FIG. 4B shows 3 setsof dots. Visualization pattern 410 and 420 could be used separately ortogether.

DETAILED DESCRIPTION

FIG. 1 shows a transverse plane view of part of the eye. For thepurposes of this invention the lens capsule 110 and the IOL 120 areshown including the iris 140 in dialated position. The anterior lenscapsule is transparent and therefore does not readily absorb light.Prior attempts to use a laser to remove tissue or make a capsulorhexisin the lens capsule have utilized (i) photodisruption producingcavitation and/or mechanical shockwave, e.g. the Q-switch Nd:YAG lasersused for posterior capsulotomy, or (ii) plasma induced ablation e.g.,the sub-pico second laser for 3-D scanned Capsulorhexis and nucleusfragmentation.

In this invention, a light absorbing agent 130 is added into or onto alayer of the anterior lens capsule 110. This agent could be abiocompatible agent (e.g. indocyanine green (ICG) or methyl blue), adye, pigment, a nanoparticle, a carbon particle, or a like.Subsequently, a light beam 150, e.g. a laser, is directed to theanterior lens capsule. The directed light beam is absorbed by the lightabsorbing agent with the intent to cause a local thermal affect on theanterior lens capsule that yields a capsulorhexis. In other words, thewavelength, power, speed of light beam movement etc. of the lightbeam(s), should be selected so that it can be absorbed by the lightabsorbing agent to cause sufficient thermal energy adjacent or at theanterior lens capsule. Furthermore, the absorption of energy should besufficient to cause a mechanical separation 210 effect at the anteriorlens capsule (FIG. 2). In general, the light beam(s) are set to be at asub-ablation level of the anterior lens capsule or are set to causelocal melting or partial/full separation of the anterior lens capsule.

The lens capsule membrane contains collagen fibrilis. As collagen isheated, it denatures, i.e. the triple-helix of collagen unwinds due tothe disruption of hydrogen bonds between the adjacent alpha chains.Furthermore, collagen undergoes a transition from its crystallinehelical structure to an amorphous structure and collagenshrinkage/contraction occurs (220-E, 220-I in FIG. 2). With theapplication of controlled heat by the directed light beam to theanterior lens capsule in the temperature range between 50 degreesCelsius and 150 degrees Celsius vaporization, membrane melting andshrinkage can occur. In another embodiment, the temperature range couldbe between 100 degrees Celsius and 120 degrees Celsius.

The capsulorhexis will be formed and the immediately adjacent tissuethat forms the resultant rim will have the contracted amorphouscollagen. This resulting rim is more elastic and resistant to tearingthan the original membrane because it comprises of this amorphouscollagen and no additional mechanical forces have stress/fractured therim during this process.

The shrinked and contracted ends 220E and 220-I separate (see 210) as aresult of the directed light the anterior lens capsule 110 into the partthat remains in the eye 110-E and the part that eventually is removed110-I for the purposes of a capsulorhexis.

One of the key aspect of the invention is the pattern of the light beamdirected at the anterior lens capsule (FIG. 3). FIG. 3 is a coronalplane view from an anterior direction of the lens capsule 110. Apredetermined closed curve 310 is defined that will be used to directthe light beam(s) and perform the capsulorhexis. The closed curve 310defines an interior and exterior area, whereby the interior area isenclosed by the closed curved 310 as shown in FIG. 3. The exterior areais anything outside the circumference of the closed curve 310. Thepredetermined closed curve distinguished an initial starting point(initial) located in the interior area. Optionally the predeterminedclosed curve also include an ending point (end) located in the interiorarea. The predetermined closed curve can be (pre)-programmed and addedto the laser and optical system used for the performance of thecapsulorhexis.

During execution, a light beam is directed to the initial point on theclosed curve 310. The selection of the position of the initial point isto create an initial starting hole, puncture or separation in theanterior lens capsule while staying clear from the ultimate position ofthe rim of curve 310 upon capsulotomy. Since the initial point is insidethe closed curve it avoids irregularity or potential tears in theresulting rim of the remaining anterior lens capsule (i.e. 220-E).

Once the initial point is created by the light beam and according to oneembodiment, the light beam is directed from the initial point of thepredetermined closed curve and continues (in the direction of the errorand in this example counterclockwise) along the pattern of thepredetermined closed curve until at least the curve is closed. In oneembodiment, this endpoint could be at end as shown in FIG. 3 i.e. at theinterior part of the closed curve again to avoid irregularity orpotential tears in the resulting rim of the remaining anterior lenscapsule or in another embodiment at any point once the curve is closedat the border of the interior/exterior area. For the purposes of acapsulorhexis, the shape of the exterior perimeter of the closed curveis preferably substantially circular or ellipsoidal.

The light beam at the initial point or the continued light beam alongthe curve path could be the same light beam or could be different lightbeams either with the same of different characteristics or parameters.The initial point could also be seen as an initial puncture beforefollowing the path of the curve and, according to this example, theinitial light beam could then be different from the continuing lightbeam.

In one embodiment, for example, but not limiting to the scope of theinvention, the initial light beam or puncture could have the followingparameters:

-   -   Speed of movement: 0 to 10 mm/second, basically dwelling on one        location or oscillating a small region for a time of about 0.25        to 3 sec.    -   Diameter of light beam on the surface: 50-600 microns.    -   Power of light beam dependent on the light absorbing agent, but        ideally less than 1000 mW.

In one embodiment, for example, but not limiting to the scope of theinvention, the continuing light beam which at least closes the curvecould have the following parameters:

-   -   Speed of movement: 0.25 to 10 mm/second, preferably in a single        pass along the curve.    -   Diameter of light beam on the surface: 50-600 microns.    -   Power of light beam dependent on the light absorbing agent, but        ideally less than 1000 mW.

In a preferred embodiment, for example, but not limiting to the scope ofthe invention, the continuing light beam which at least closes the curvecould have the following parameters:

-   -   Speed of movement: 0.5 to 3 mm/second, preferably in a single        pass along the curve.    -   Diameter of light beam on the surface: 100-300 microns.    -   Power of light beam dependent on the light absorbing agent, but        ideally less than 600 mW.

The continuing light beam is preferably accomplished in a single pass toprovide as much consistency in the rim pattern as possible with the rimbeing formed with the same (or at least similar) thermal conditions. Thesingle pass is also important to ensure completion of the capsulorhexiseven if there is slight movement of the eye relative to the trajectory.Preferably and in particular for the continuing light beam a CW laser isused. However, a high-frequency pulsed (>1 KHz) pulsed laser, e.g. asubpico Q-switch laser could also be used. In one embodiment, thewavelength could be in the infrared to near infrared region of thespectrum, thus it would be near invisible to the patient, providingminimal irritation.

A visible aim beam or pattern(s) could be present to project thelaser-cutting or laser-separating trajectory or to project at least partof the closed curve on the anterior lens capsule surface. Thevisualization patterns are useful to bring the laser into focus on thelens capsule surface and to allow the physician to select the locationand size of the capsulorhexis. To get the visible aim beam into focus isoften hard, especially for a ring, since you are looking for a sharpedge on the aim beam or its smallest width of the line.

To assist focusing the method described herein could be extended byprojecting a visualization pattern 410, which preferably coincides withthe perimeter of the closed curve (e.g. a circular pattern in thisparticular example) (FIG. 4). In other words, a key aspect of thisinvention is that visualization pattern 410 is different from thepattern of the closed curve 310 (i.e. 410 does not include the initialand end paths in the interior side of the closed curve). FIG. 4 alsoshow another visualization pattern with at least 3 set of dots 420 toassist in focusing the light beam(s), whereby the set of dots prefereblyare visualized along the interior-exterior border of the closed curve310. Such a pattern of discrete dots 420 is far easier to focus and ororientating the eye of the patient. Pattern 410 and 420 could be usedseparately or combined.

In one embodiment, for example, but not limiting to the scope of theinvention, the visualization light beam could have the followingparameters:

-   -   Speed of movement: greater than 450 mm/second.    -   Diameter of light beam on the surface: 50-600 microns    -   Power of light beam is dependent on the light absorbing agent,        with an average power of less 1 mW.    -   Wavelength is in the visible spectrum.

As one of ordinary skill in the art will appreciate, various changes,substitutions, and alterations could be made or otherwise implementedwithout departing from the principles of the present invention. Forexample, in one variation the methods described herein could be variedfrom the applciation of a capsolurorhexis to thermally cutting orpartially/fully separating tissue or collagen-containing material. Inyet another variation, the laser-assisted capsulorhexis does notpenetrate the full thickness of the anterior lens capsule, but there isa groove in the capsule surface. The full thickness capsulorhexis couldthen be completed manually with a CCC with the groove guiding the manualtear. In still another variation, additional methods for fixating theeye could be added for example by placing a surgical contact lens on theeye. This will minimize the eye motion. Moreover, the scanning devicecould or any other device could hold the contact lens thus restrictingthe eye motion further. The use of a contact lens could also increasethe ability to focus the light with a great numerical aperture, allowingmore accurate focusing on the specific target tissue and reduction oreliminate potential light beam exposure to the retina, cornea, foveaposterior capsule and cataractus lens and therewith less of adisturbance/irritation to the patient. Accordingly, the scope of theinvention should be determined by the following claims and their legalequivalents.

1. A method of thermally separating tissue, comprising: (a) defining apredetermined closed curve at said tissue, wherein said predeterminedclosed curve defines an interior and an exterior; (b) directing a lightbeam at an initial and interior point of said predetermined closedcurve; and (c) continuing and further directing said light beam startingfrom said initial and interior point of said predetermined closed curvealong the remaining path of said predetermined closed curve until atleast the curve is closed, wherein said light beam is: (i) characterizedto remain at a sub-ablation level of said tissue at said curve, (ii)characterized to cause melting of said tissue at said curve, or (iii)capable of thermally puncturing or separating said tissue.
 2. The methodas set forth in claim 1, further comprising adding a light-absorbingagent into or onto said tissue, wherein the wavelength of said lightbeam is capable of being absorbed by said light absorbing agent.
 3. Themethod as set forth in claim 1, wherein the continued light beam ends ata final and interior point of said predetermined closed curve.
 4. Themethod as set forth in claim 1, wherein the initial and the continuinglight beam are the same type of light beam or different types of lightbeams.
 5. The method as set forth in claim 1, wherein said light beam isa light beam from a CW laser.
 6. The method as set forth in claim 1,wherein the exterior path of said predetermined closed curve issubstantially circular or ellipsoidal.
 7. The method as set forth inclaim 1, further comprising directing a visualization pattern at saidtissue, wherein the visualization pattern (i) is different from saidpredetermined closed curve or (ii) comprises of at least 3 set of dots,wherein each of said set of dots is distributed along theinterior-exterior border of said prederermined closed curve.
 8. A methodof thermally ablating tissue, comprising: (a) defining a predeterminedclosed curve at said tissue, wherein said predetermined closed curvedefines an interior and an exterior; (b) directing a light beam at aninitial and interior point of said predetermined closed curve; and (c)continuing and further directing said light beam starting from saidinitial and interior point of said predetermined closed curve along theremaining path of said predetermined closed curve until at least thecurve is closed, wherein said light beam is: (i) characterized to remainat thermal ablation level of said tissue at said curve, or (ii) capableof puncturing or separating said tissue.
 9. A method of performing acapsulotomy, comprising: (a) adding a light-absorbing agent into or ontoan anterior lens capsule; (b) defining a predetermined closed curve atsaid anterior lens capsule, wherein said predetermined closed curvedefines an interior and an exterior; (c) directing a light beam at aninitial and interior point of said predetermined closed curve; and (d)continuing and further directing said light beam starting from saidinitial and interior point of said predetermined closed curve along theremaining path of said predetermined closed curve until at least thecurve is closed, wherein said light beam is: (i) characterized to remainat a sub-ablation level of said tissue at said curve, (ii) characterizedto cause melting of said tissue at said curve, or (iii) capable ofthermally puncturing or separating said tissue.
 10. The method as setforth in claim 9, further comprising adding a light-absorbing agent intoor onto said anterior lens, wherein the wavelength of said light beam iscapable of being absorbed by said light absorbing agent.
 11. The methodas set forth in claim 9, wherein the continued light beam ends at afinal and interior point of said predetermined closed curve.
 12. Themethod as set forth in claim 9, wherein the initial and the continuinglight beam are the same type light beam or different types of lightbeams.
 13. The method as set forth in claim 9, wherein said light beamis a light beam from a CW laser.
 14. The method as set forth in claim 9,wherein the exterior path of said predetermined closed curve issubstantially circular or ellipsoidal.
 15. The method as set forth inclaim 9, further comprising directing a visualization pattern at saidtissue, wherein the visualization pattern (i) is different from saidpredetermined closed curve or (ii) comprises of at least 3 set of dots,wherein each of said set of dots is distributed along theinterior-exterior border of said prederermined closed curve.
 16. Amethod of performing a partial depth tissue separation, comprising: (a)adding a light-absorbing agent into or onto a tissue; and (b) directinga light beam at said tissue, wherein the wavelength of said light beamis capable of being absorbed by said light absorbing agent, wherein saidlight beam is: (i) characterized to remain at a sub-ablation level ofsaid tissue or (ii) characterized to cause melting of said tissue, andwherein said light beam is characterized to only cause partial depthseparation or puncturing of said tissue.
 17. The method as set forth inclaim 16, wherein said tissue is an anterior lens capsule.
 18. Themethod as set forth in claim 16, further comprising: (a) defining apredetermined closed curve at said tissue, wherein said predeterminedclosed curve defines an interior and an exterior; (b) directing a lightbeam at an initial and interior point of said predetermined closedcurve; and (c) continuing and further directing said light beam startingfrom said initial and interior point of said predetermined closed curvealong the remaining path of lo said predetermined closed curve until atleast the curve is closed.
 19. A method of thermally cutting, separatingor contraction of a collagen-containing material, comprising: (a) addinga light-absorbing agent into or onto said collagen-containing material;and (b) directing a light beam at said collagen-containing material,wherein the wavelength of said light beam is capable of being absorbedby said light absorbing agent, and wherein said light beam is: (i)characterized to remain at a sub-ablation level of saidcollagen-containing material, (ii) characterized to cause melting ofsaid collagen-containing material, or (iii) capable of thermallypuncturing or separating said collagen-containing material.
 20. Themethod as set forth in claim 19, further comprising: (a) defining apredetermined closed curve at said collagen-containing material, whereinsaid predetermined closed curve defines an interior and an exterior; (b)directing a light beam at an initial and interior point of saidpredetermined closed curve; and (c) continuing and further directingsaid light beam starting from said initial and interior point of saidpredetermined closed curve along the remaining path of saidpredetermined closed curve until at least the curve is closed.